How Neutral Density Filters Work and How to Use Them For Better Photography

Taking good pictures isn’t nearly framing your topic and studying composition. Studying how to management how a lot gentle enters your digital camera and for a way lengthy might help you are taking images that elude the typical photographer. Neutral density filters are a strong instrument in direction of that finish. Right here’s what they’re and how to use them.

Neutral density filters (or ND filters) scale back the general depth of the sunshine that passes by them, with out affecting the coloration of that gentle. When you place an ND filter like these over the lens of a DSLR digital camera, it permits much less gentle to move by, which provides you the flexibleness to open the aperture wider or expose a photograph for longer than you’ll have the opportunity to in any other case.

Why Neutral Density Filters Matter

To grasp why that is useful, we’d like to look a bit at how a digital camera works. Once you take an image along with your digital camera, the aperture opens to permit gentle to hit your digital camera’s sensor. On extra superior cameras like DSLRs, you’ll be able to modify two key components of that course of: the scale of the aperture (measured in f-stops), and the shutter velocity, which determines how lengthy the aperture is opened. These two numbers mixed decide how a lot gentle hits your digital camera’s sensor.

This info is necessary for a ton of widespread pictures duties. If you need to a sports activities recreation, for instance, you’ll want to use a quick shutter velocity so as to scale back movement blur. In case you take footage at night time, you’ll both want a wider aperture so as to let in additional gentle, or a slower shutter velocity (and a tripod) to catch sufficient gentle for a well-lit image. You may even do cool issues like use an extra-long publicity to take footage of fireworks.

Neutral density filters provide you with extra flexibility to play with these settings. For instance, a protracted outside publicity with a large aperture at night time might look good, however for those who used those self same settings in the course of the day, your images will be a blown out, overexposed mess. With an ND filter, nonetheless, you’ll be able to filter all of the daylight coming into your digital camera and nonetheless use a protracted publicity to get the impact you need with out ruining your photograph.

For instance, take into account the above picture, comprised of two related images from Wikimedia. The left facet of this photograph was taken with an publicity of 1/30th of a second and no filter. The fitting facet, nonetheless, was shot with an ND1000 filter, which permits solely .1{bee317a2559d13a75caaf6af5f4d02a14abe32641887c9defccb6fb9d1912473} of sunshine by it. That photograph was taken with a 57 second publicity. Sure, which means the shutter was open for almost a full minute. Regardless of the for much longer publicity time, the filtered on the precise nonetheless appears to be like comparatively regular. The one change is that the floor of the water (which might’ve been in fixed movement whereas the shutter was open) now has a silky clean look. You may continuously see this impact used to create dazzling photos of waterfalls, oceans, and different surroundings the place one ingredient of a scene strikes however the remainder of the shot stays stationary.

You may also use ND filters to selectively management the sunshine in a scene. Graduated ND filters function clear glass on one facet of the filter, a full ND filter on the opposite facet, and a small gradient in between. That is useful if you need to take an image of a scene the place one half of the picture (say, the sky) is very shiny, however the different half (say, the bottom) is darker. Place the darker half of the graduated ND filter over the sky, and the sunshine coming into your digital camera can be extra even. You may expose for the bottom with out blowing out the sky.

Methods like this are widespread on this planet of movie, as effectively. Everytime you see a scene with individuals in entrance of a window, likelihood is good that the window is layered with an ND filter gel that reduces the sunshine shining by. In case you have been on set, the home windows would look dim, since your eyes do a greater job of distinguishing between the darker room and brighter outside. Nevertheless, if you shoot the room by a digital camera, that ND gel makes the window look loads higher. More often than not, photographers gained’t want to ND gel a window, however it’s necessary to concentrate on the sunshine sources in your arrange and concentrate to how to correctly filter them to make the lighting in your scene even.

How to Use ND Filters In Your Photography

Above: Fountain shot at f/6.three and 1/200 second publicity. Beneath: f/6.three and zero.four seconds (or 80x longer) with ND16 filter. Notice: some coloration correction was carried out to the second photograph to repair a coloration solid from the ND filter.

To get began with ND filters, you’ll want to know the notation used to price them. Whereas ND filters use a number of complicated notations, the most typical is the ND quantity, typically written as ND2, ND4, ND8, and so on. You may consider the quantity on this notation as the underside of a fraction. An ND2 filter permits half of all gentle by it. An ND4 filter permits 1/4th of all gentle by it. An ND8 filter permits 1/eighth of all gentle to move by, and so on.

You may discover the numbers for these ND filter rankings double with every new filter. With a number of exceptions, most ND filters you discover can be a successive energy of two. The explanation for that is each time you halve the quantity of sunshine that passes by a filter, you successfully scale back the sunshine coming into your digital camera by one entire f-stop. So, an ND2 filter reduces the sunshine by one f-stop. An ND4 filter reduces it by two f-stops, and on and on.

It is a helpful shorthand if you’re calculating your gentle wants for a shot. Say you’re taking a photograph of a waterfall and you need that silky clean search for the water. You’re taking a traditional shot with an f-stop of f/22—this very small aperture ensures your entire scene is in focus—utilizing Aperture Precedence mode in your digital camera. At this setting, say your shutter velocity for a correctly uncovered photograph can be one second (to make the mathematics straightforward for now).

Something longer than one second and your photograph can be blown out and too shiny. So, you place an ND16 filter and an ND4 filter over your digital camera. This successfully reduces the sunshine by six whole stops. So, to compensate along with your shutter velocity, you’ll want to double the size of your publicity six instances. A one second publicity, doubled six instances (1 * 2 * 2 * 2 * 2 * 2 * 2) comes out to 64 seconds. You’re gonna want Bulb Mode for this one, however now you’ve calculated your correct publicity time.

You may also use this shorthand for taking primary panorama pictures. Typically, the sky is brighter than the bottom, so to take a very good image of each, you need the sky and the bottom to be inside about one f-stop of one another. So, for instance, in case your sky is correctly uncovered at f/16, whereas the bottom is correctly uncovered at f/5.6, then they’re three full stops other than one another. However you now know you’ll be able to place a graduated ND4 filter (which reduces gentle by two stops) over the sky to deliver the sunshine nearer collectively. Now you’ll be able to take an image of the panorama with out blowing out or underneath exposing half the body.

ND filters provide you with a entire new diploma of flexibility that you would be able to’t at all times get by adjusting your aperture or shutter velocity alone. They’re additionally comparatively low cost. This package is the one I used for the images of the fountain above. It prices lower than $30, comes with ND2-ND16, and quite a lot of adapter rings to your DSLR digital camera. Whereas the glass isn’t excellent (you could want to do some coloration correction later), it’s a helpful instrument to have in your bag.